Lifting unit



J. W. KAPPEN LIFTING UNIT July 9, 1963 5 Sheets-Sheet l Filed Feb. l5,1957 n mm.

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J. W. KAPPEN LIF'TING UNIT July 9, 1963 ."5 Sheets-Sheet 2 Filed Feb. 131957 J. W. KAFFEN July 9, 1963 LIF'TING UNIT 3 Sheets-Sheet 5 Filed Feb.l5, 1957 INVENTOR //A/l/V' KHP/57V BY m United States Patent 34996595LIFTING UNIT John W. Kappen, 243 Kenwood Ave., Dayton, Ohio Filed Feb.13, 1957, Ser. No. 640,019 4 Claims. (Ci. 214-674) This inventionrelates to lifting units, and has especial although not limitedreference to the loading and unloading of trucks in circumstances wherethe level of the truck bed interior is not aligned with the iioor ordock level from which goods are to be placed into the truck or to whichgoods within the trucks are to be removed.

The object of the invention is to simplify the construction as well asthe means and mode of operation of lifting units, whereby such units maynot only be economically manufactured, but will be more eicient andsatisfactory in use, adaptable to a wide variety of applications, randbe unlikely to get out of order.

A further object ofthe invention is to provide a lifting unit asdescribed including a load platform which can be quickly land easilyelevated and lowered between truck level and dock or ground level.

Another object of the invention is to provide a lifting unit presentinga load platform accessible from multiple sides thereof for loading andunloading whereby to simplify its use and to permit the servicing of aplurality of trucks simultaneously.

A further object of the invention is to facilitate the movement of handcarts onto and off of the loading platform by providing for tiltingyadjustment thereof relative to the floor or ground level.

Still another object of the invention is to provide a simpliiiedhydrauliic actuating means for the lifting unit, characterized by aconstruction yand arrangement of parts enabling the tilting of the loadplatform in a timed relation to the elevating and lowering thereof.

A still further object of the invention is to provide a simplifiedconstruction for the lifting unit according to which the -unit may beadapted for portability or for permanent installation.

A further object of the invention is to provide a lifting unitpossessing the advantageous structural features, the inherentmeritorious characteristics and the mode of opera-tion herein mentioned.

With the above and other incidental objects in view as will more fullyappear in the specification, the invention intended to be protected byLetters Patent consists of the features of construction, the parts `andcombination thereof, and the mode of operation as hereinafter describedor illustrated in the accompanying draw-ings, or their equivalents.

Referring to the accompanying drawing wherein is shown one but obviouslynot necessarily the only form of embodiment of the invention,

FiG. l is a view in perspective of a lifting unit in accordance with theillustrated embodiment of the invention, showing the lift assembly inlowered position and the load platform in an operating extendedposition;

FIG. 2 is a View similar to FIG. l, at a reduced scale, showing the loadplatform rocked or folded to a substantially vertical position, forpurposes of storing or transporting;

FIG. 3 is a detail View, in perspective, of the base supporting meansand a part of the lift assembly, the latter being in exploded relationin order better to illustrate the construction and arrangement of theparts;

FlG. 4 is a view in cross section through a vertical post made up oftelescoping parts of the lift assembly and supporting apparatus;

FIG. 5` is a diagram of hydraulic and electrical circuits provided for4operation of the lifting unit;

FIG. 6 is a `detail view in side elevation showing the load platform infolded position, and the means for adjusting it to and from theillustrated position.

FIG. 7 isa fragmentary perspective View of the base;

FIG. 8 is a fragmentary perspective view of the intermediate supportassembly.

Like parts are indicated by similar characters of reference throughoutthe several views.

Referring to the drawings, the lifting unit in its illustrativeembodiment is of a fabricated steel construction, the several elementsof each integrated unit being welded or otherwise permanently unitedwith one another. The unit includes a base 1t) formed of relatively flatand wide plates 11 in parallel relation to one another andinterconnected at their one ends by a cross member 12. The opposite endsof the ibase plates 11 extend as projecting reduced width fingers 13toward what may be considered to be the front of the lifting unit, thebottoms of such fingers lying in the same' plane `as the bottoms of theplates 11, with the result that the base is elongated in a directionfrom the front to the rear thereof for a relatively long contact withthe ground or floor level upon which the lifting unit is received. Thebase is adapted to be bolted to a stationary foundation tor to beinstalled upon wheels or casters for portability. Also forming a part ofthe ibase assembly is a unitary bridge 14 which spans the plates 11 at apoint near the rear thereof or adjacent to the cross member 12. Stillfurther, in upstanding walls of the plates 11 are yaligned openings 1Sand 16 providing bearings for the opposite ends of `a shaft 17.

The base 1t) provides a mounting for an intermediate support assembly2i) comprised of parallel legs 18 which are received between the lelgs11 of the base assembly 10 and are interconnected at their one ends by across member 19 which is in substantially underlying relation to thebridge 14. Also interconnecting the legs 18 is an intermediate crossmember 21 having in the mid portion thereof an upwardly opening thrustbearing 22. Transverse openings 23 yand 24 in the legs 1S register withthe openings 15 and 16, in the assembled position of the parts, and havethe shaft 17 passed therethrough. The construction and arrangement ofparts is such that the intermediate support 2t? is mounted on the shaft17 to be rocked to and fro upon the shaft as `a pivot, the direction ofrocking motion being toward the front and toward the rear of the unit asbefore designated.

At the ends of the cross member 21, on the legs 1S, are respectiveupstanding guide posts 25 and 26, each made of channel shaped members,as seen in FIG. 4, the channel shaped members being in opposite relationwith their longitudinal side edges in contact with one another andwelded to make up a unitary post. At their bottom ends, the posts 25 and26 are in intersecting relation to upstanding rib formations on the legs18 and on the cross member 21 and are welded thereto for permanentinterconnection of the parts. The guide posts further are braced by abrace member 27 which is anchored to the rear of the legs 18 and extendsupward to an intermediate point between the ends of the posts, whereintegral parts 28 of the brace enter `and are welded between the channelshaped portions of the posts 2S and 26.

Also interconnecting the base assembly 10 and the intermediate supportassembly 2.0 are hydraulic cylinder devices 29 and 31, each comprising acylinder anchored, as by brackets 32 to the underside of the bridge 14and a piston anchored, as by brackets 33 to the rear cross member 19 ofthe assembly 20. The legs 18 of the assembly 20 extend in an upwardlydivergent manner from an intermediate point beneath the pivot openings23 and 24. The latter point is adapted substantially to rest PatentedJuly 9, 1963 u upon the same surface as the plates 11 of the base 10i,while the elevation of the ends of the legs lpermit the assembly 26 as aunit to rock in a forward and rearward direction relatively to the base16 and to the supporting surface upon which the unit rests.

The intermediate support assembly 26 provies a mounting for a liftassembly 34 which includes sleeves 35 and 36 in such teiescopingrelation to the posts 25 and 26 as to connect the lift assembly. to theintermediate support 4assembly for unison rocking motion therewith andfor relative elevating and lowering motions. The sleeves 35 and 36 areeach made up of opposed channel shaped members like the members whichmake up the posts 25 and 26 and at their rear are cut by longitudinalslots 37 and 38 which permit the lift assembly to slide vertically uponthe posts 25 and 26 without interference With the parts 23 of the brace27. The sleeves 35l and 36 are integrally connected by upper and lowercross members 39 and 41, the former of which has a downwardly openingthrust bearing 42 in aligned, opposed relation to the similar bearing 22in the cross member 21 of the intermediate support 20:. interposedbetween the thrust bearings 22 and 42 is a hydraulic cylinder device 43comprising a cylinder based in one of the bearings and a relativelyextensible piston received in the other. It will be understood that thehydraulic devices 29, 31 and 43 are adapted to be supplied with ahydraulic fluid under pressure and when so supplied will relativelyextend the pistons therein with the result that the intermediate support20 and mounted lift assembly will rock in a rearward directionrelatively to the base and with the further result that the liftassembly will elevate or rise upon the posts 25 and 26.

Extending forwardly from the lift assembly 34, and in effect forming apart thereof is a platform 44- made rectangular and planar in form ofsuitable rigid materials. On what may be considered to be the rear edgeof the platform 44 is mounted a frame work 45 the purpose ofV which isto present two pairs of bars 46 and 47 and 48 yand 49 in laterallyspaced apart relation at such rear edge of the platform. The bars 46 and47 are adapted toreceive between them the lower end of the sleeve 35 ofthe lift assembly while the bars 48 and 49Y similarly receive the lowerend of the sleeve 36. On each of the bars 46 yand 47, in relativelyelevated` relation to the surface of the platform, is a forwardlyprojecting arm 51. Similarly, on each. of the bars 48 and 49 isaforwardly projecting arm 52. On the front of each of the sleeves 35 and36 is a block 53 adapted to be received between a respective pair ofarms 51 and 52. A shaft 54 extends through aligned openings in lthe arms51 'and 52 and blocks 53 and so pivotally connects the platform 44'tothe lift assembly. The rear edge of the platform engages the lower endsof the sleeves 35 and 36, beneath the blocks 53, in the assembledposition of the parts so that the platform is limited in its downwardrocking motion to a position in which it extends approximately normal tothe vertical axis of the sleeves 35 and 36. Rocking motion of theplatform upward or to what may be termed a folded position relatively tothe upright sleeves 35 land 36 is possible and the platform may be heldin such a position by engagement of a latch 54 swingably mounted uponthe sleeve 34 with a notch 55 formed in the bar 49.

In such a rocked or raised position, which the platform is made toassume for more convenient storage or like purposes, the parts assumethe position substantially as shown in f-ull lines in FIG. 6. Toaccomplish its movement to this position, there is provided a bracket 56on the sleeve 36, on which sleeve is a pulley wheel 57. On a relativelystationary part 2S of the brace 27 is another pulley wheel 58. A chain59 is attached at 61 at its one end to the bracket 56. From the point61, the chain 59` extends downward and around the pulley wheel 58 upwardand around the pulley wheel 57 and at its other or opposite end isreleasably hooked upon a pin 62 in the platform 44. In the normal use ofthe lifting unit, the chain 59 is disengaged `from the platform 44. WhenAthe chain is engaged witltpin 62 in the platform, however, it will beseen that a subsequent elevating motion of the lift assembly will pullthe chain 59 over the pulley wheel 57, in effect shortening the lengthof the chain from the pulley wheel to the pin 62 and drawing theplatform 44 gradually upward until it reaches the upright positionillustrated. The lift assembly may be subsequently lowered, withoutlowering the platform, if in the interval the latch 54 is engaged in thenotch 55 of the bar 49 in the manner indicated. When it is desired torelease the platform for lowering, an elevating motion of the liftIassembly is continued slightly above the position shown in FIG. 6 whichwill result in the latch 54 rising free of the bar 49. Accordingly, ifthe latch is now moved to an ineffective position, a subsequent loweringof the lift assembly will be accompanied by a lowering or downwardlyrocking motion of the platform 44 to its normal operating position.

To contr-ol the rocking motion of the lift assembly, and of theelevating .and lowering thereof, there is provided, as shown in FIG. 5,an electric and hydraulic circuit which may be substantially `as thereindicated. Thus, electrical conductors 63 and 64 extend from a source ofelectrical power (not shown) to an electric motor operatedpump 65 and inone of such lines is a switch 66. The pump 65 is interposed in ahydraulic circuit and operates to withdraw hydraulic uid from a place ofstorage 67 and directed through a common conductor 68 to parallelconductors 69 and 71, one of which leads to the hydraulic devices 43 andthe other to the devices 29- 31. Within the conduits 69 and 71 varerespective metering orifices or valves 72 and 73. The conduit 71 isdivided beyond the valve '73 intoseparate conduits leading to theindividual devices 29 and 31. Accordingly, when the switch 66 is closed,the pump `65 is energized and draws fluid from the place of storage 67and directs it by Way of the conduits 68 and 69-71 simultaneously to thehydraulic device 43 `and to the pair of devices 29-31. In combination,lthe devices 29-31 present a greater piston area to the pressure fluidthan does the device 43 with the result that the devices 29-31 are moreresponsive to the pressure of the fluid than is the device 43.

Relating the hydraulic circuit to the operation of the lifting unit, theparts normally assume a position in which the intermediate support 2t)and lifting assembly 34 thereon are lrocked in a forward direction sincethe platform 44 projects in relatively offset relation to the base 10and provides a weight tending to rock the support 20 forwardly about thepivot represented by shaft 17. Similarly, the weight of the platformmaintains the lift assembly normally in a lowered position. With thelift assembly so lowered and so rocked in a forward direction, theplatform takes up an angular position relatively to the base andrelatively to the ground `surface or floor level, the leading edge orthat edge in opposing relation to the rear edge ofthe platform beingtilted or inclined toward the ground. In conjunction with a wedge shapedpart 74, which may be permanently installed in the ground or floorsurface or be pivotally attached to the leading edge of the platform,the platform when thus tilted provides a ramp of low inclination uponwhich hand carts, fork lift trucks and the like may readily move fromthe ground or floor surface. Upon energizing of the pump 65 the initialhydraulic action is to rock the intermediate support 26 and liftassembly 34, including the platform 44, toward the rear of the unit in amanner to restore the platform to a position approximately parallel tothe ground or floor surface. Then, as the operation of the pump 65continues, the lift assembly and platform are elevated relatively to thebase and intermediate support to a selected high level position. In thelowering of the lift assembly, the parts retain the rearwardly rockedposition described until the lift assembly reaches its fully loweredposition and pressure is released from the hydraulic device 43.Thereupon pressure similarly is released from the devices 29 and 31,enabling the weight of the platform 44 to rock the intermediate support2t) forwardly and restore the platform to an inclined position whereinthe load may be more easily brought onto or removed from the platform.

There may also, as indicated, be used in similar manner with theplatform, side wings or panels 75 and 76. In this connection, it will beapparent that the platform 44 extends laterally in a relatively free andunobstructed manner from the base and lift assembly of the lifting unitproper whereby not only the far or leading edge of the platform isavailable for the entrance and exit of goods but the both sides as well.The platform accordingly is accessible from three sides for loading andunloading and lends itself to an arrangement by which a plurality oftrucks may be backed up to the lifting unit from dierent directions andtheir interiors loaded or unloaded simultaneously through use of thelifting unit.

Referring .again to the hydraulic and electrical circuit of FIG. 5, thismechanism will preferably provide for interrupting the elevating andlowering movements of the lift assembly at any selected point, with theassembly being positively held in such position. According to oneconcept of control apparatus for this purpose, there is interposed inthe common hydraulic conduit 68 a check valve 77 opening toward thehydraulic devices and closing toward lthe pump. Also, there is provideda by-pass return passage 78 from the conduit 63 to the tank 67 inby-passing relation to the pump 65' and check valve 77. ln the passage78 is a solenoid valve 79, normally closed and adapted to be energizedin response to the closing of a switch 81 in a circuit S2 connecting thesolenoid valve across `the electrical conductors 63 and 64. In theoperation of this form of the system, the switches 66 and 81 are bothnormally open, with the valves 77 and 79 both normally closed, Uponclosing of switch 66, hydraulic tiuid is forced by the pump 65 past thecheck valve '77 and to the hydraulic devices as described. When the liftassembly has achieved a height as desired, the switch 66 is released,.and operation of the pump `65 discontinued. The valve 77 closes and thehydraulic fluid in `advance thereof accordingly is trapped, whereby vthelift assembly and platform are retained in their selected elevatedposition. When it is desired to lower the platform, switch S1 is closedwhereby to close a circuit through the solenoid valves 79, opening thevalve for return iiow to the tank or place of storage 67 by way of theby-pass passage 78. Lowering of the lift assembly will in this mannercontinue as long as the switch 81 is held closed and may be discontinuedat any time by release of the switch. `It will be understood in thisregard, and in regard to the tilting action of the platform 44 whenfully lowered, that the platform may be moved between elevated andlowered positions intermediate the upper most and lower most positionsfreely without tilting of the platform. The rate of descent of theplatform is controlled by the metering valves 72 and 73.

As shown in FIGS. 7 and 8 an adjustable positive stop is provided tolimit the rocking motion of the intermediate support assembly Zi)relative to the base assembly 10. Such stop comprises an adjustablescrew 83 having threaded engagement with the lower portion of the vrearcross member 19 in the intermediate support assembly 20. This screw 83has an enlarged pad or shoulder on the bottom thereof for engagementwith a projecting portion 84 extending `inwardly from the rear crossmember 12 of the base 10. Thus -by adjustment of the screw S3 relativeto the cross member 19 the degree of rocking motion of the intermediatesupport member relative to the base member in a clockwise direction canbe accurately predetermined and controlled.

In many installations the unit compris-ing the subject matter of thisapplication is so located relative to a loading dock that it preventsnormal use of the dock by trucks which do not require the use of thepresent lifting unit. In such instances the folding of the load platformto the position in FIG. 2 permits trucks to pass the lifting unit so asto be able to back up to the loading dock in a normal fashion.

From the above description it will be apparent that there is lthusprovided a device of the character described possessing the particularfeatures of advantage before enumerated as desirable, but whichobviously is susceptible of modification in its form, proportions,detail construction and arrangement of parts without departing from theprinciple involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has beendescribed in language more or less specific as to structural features,it is to be understood that the invention is not limited to the specificfeatures shown, but that the means and construction herein disclosedcomprise but one of several modes of putting the invention into effect,and the invention is therefore claimed in any of its forms ormodifications within the legitimate and valid scope of the appendedclaims.

What is claimed is:

l. A lifting unit, including a base, rocking means supported by saidbase for relative rocking movement, a lift assembly supported by saidrocking means for unison rocking and relative elevating and loweringmotions, the weight of said lift assembly being disposed to rock saidrocking means -in one direction, a hydraulic piston and cylinderconnection between said base and said rocking means, another hydraulicpiston and cylinder connection between said rocking means and said liftassembly, means for supplying hydraulic fluid under pressuresimultaneously to the first said connection in a marmer to rock saidrockin-g means in the opposite direction and to the said otherconnection in a manner to elevate said lift assembly, said connectionspresenting a differential piston area to the hydraulic fluid to effectsaid rocking and elevating motions in a predetermined sequence.

2. A lifting unit, including a base, a lift assembly supported on saidbase for relative elevating and lowering motions, a platform pivotallyconnected to said lift assembly, means limiting pivotal motion of saidplatform in one direction to cause said platform to assume normally agenerally laterally extending position in approximately parallelrelation to ground level, means for elevating and lowering said liftassembly while said platform remains in said laterally extendingposition, and a releasable, normally disabled connection between saidlift assembly, said base and said platform utilizing motion of said liftassembly in an elevating direction to .move said platform pivotally to aposition approximately perpendicular to ground level.

3. A lifting unit according to claim 2, characterized by means forlatching said platform in perpendicular position as describedirrespective of movement of the lift assembly.

4. yA lifting unit, including a base, rocking means supported by saidbase for relative rocking movement thereon, a lift assembly o-n saidrocking means mounted for unison rocking motion and relative elevatingand lowering movements, said lift assembly including a load platformconnected for disposition in such offset relation to said base that theweight thereof tends to rock said rocking means in a direction to tiltan edge of said platform toward the ground surface when said liftassembly is in its lowermost position, control means for rocking saidrocking means in the opposite `direction to place said platformapproximately parallel to the ground surface, elevating the liftassembly including said load platform, and for maintaining said platformin its position approximately parallel to the ground surface throughoutvertical movement thereof, characterized by said control means includinga rst assembly of hydraulic piston and cylinder elements interconnectingsaid base and said rocking means, a second assembly of hydraulic pistonand cylinder elements interconnecting said lift assembly and saidrocking means, and means for supplying hydraulic fluid under pressure toboth said assemblies of piston and cylinder elements simultaneously, andto discontinue such supply simultaneously, the first assembly ofcylinder piston elements exposing a relatively larger area to thehydraulic fluids so that the rocking of said load platform from tiltedposition precedes elevation thereof and the rocking to tilting positionlfollows lowering thereof.

UNITED STATES PATENTS Howell Nov. 5, Johnson May 23, Healy Sept. 25,Hegarty Apr. l, Gibson May 1'4,

FOREIGN PATENTS v Great Britain Dec. 3,

1. A LIFTING UNIT, INCLUDING A BASE, ROCKING MEANS SUPPORTED BY SAIDBASE FOR RELATIVE ROCKING MOVEMENT, A LIFT ASSEMBLY SUPPORTED BY SAIDROCKING MEANS FOR UNISON ROCKING AND RELATIVE ELEVATING AND LOWERINGMOTIONS, THE WEIGHT OF SAID LIFT ASSEMBLY BEING DISPOSED TO ROCK SAIDROCKING MEANS IN ONE DIRECTION, A HYDRAULIC PISTON AND CYLINDERCONNECTION BETWEEN SAID BASE AND SAID ROCKING MEANS, ANOTHER HYDRAULICPISTON AND CYLINDER CONNECTION BETWEEN SAID ROCKING MEANS AND SAID LIFTASSEMBLY, MEANS FOR SUPPLYING HYDRAULIC FLUID UNDER PRESSURESIMULTANEOUSLY TO THE FIRST SAID CONNECTION IN A MANNER TO ROCK SAIDROCKING MEANS IN THE OPPOSITE DIRECTION AND TO THE SAID OTHER CONNECTIONIN A MANNER TO ELEVATE SAID LIFT ASSEMBLY, SAID CONNECTIONS PRESENTING ADIFFERENTIAL PISTON AREA TO THE HYDRAULIC FLUID TO EFFECT SAID ROCKINGAND ELEVATING MOTIONS IN A PREDETERMINED SEQUENCE.